Pressure Reducing Valve

durango118July 18, 2010

Please, if anyone can help with info it's greatly appreciated. I've noticed recently while running washing machine and irrigation or any combination of water in the house I'm getting some weird sounds knocking. Mostly from where the pressure reducing valve is located.

I had a plumber come check it out yesterday...he gave me a quote of $675 to replace it, saying that it's not as simple as just unscrewing the bolts and and re-attaching. He says he has to cut the pipe and re-solder them. I checked the whole sale price of these and they look like they can average between $75 and $150. Which means I'm probably paying about $450 in labor.

I can't find any info on this item unless its somehow connected to a water heater. Seems like they go hand in hand. And he did ask questions about the water heater but never mentioned it might need to be replaced. Is he going to come in and tell me I need a new water heater?? This is my fear and I don't mind paying buy I hate not knowing whats up.

Pressure reducing Valves (PRVs) are usually installed at the water service entrance and sometimes at the house side of the water meter outside but I've never seen one at the water heater. Are you confusing a Pressure Reducing Valve (PRV) with the Temp and Pressure (T&P) relief valve on the water heater?

You may be experiencing water hammer and that usually manifests itself as pipes banging or rattling after quickly shutting of a valve but you say it is localized at the PRV, right?

First... I assume you're on a water system? Do you know the supply pressure from the water department?

Second... is there a thermal expansion tank installed on the cold water line to the water heater?

Third... get yourself a pressure gauge with a tattletale needle that screws on to a hose bib like this and see what the static (no water running) pressure is in the plumbing. It should be under 80 psi static.

Fourth... if you want to read up on pressure reducing valves (PRVs) there's more info than you'll want here

Fifth... unless you have a particularly exotic PRV or a very difficult installation I'd call another plumber cause $675 sounds pricy.

justalurker
Thanks so much for the quick response, I'm getting ready right now to go to Lowes for a pressure gauge. Sorry if I'm a little unclear, (I'm a little unclear myself) This is how it unfolded yesterday....plumber arrives, we turn on several things (washer, outside hose, sink) and there is a swishing and knocking sound pretty close to where the PRV is in the garage. Right away he says it needs to be replaced. When he comes in the house he asks about how old the water heater is, (about 3 yrs) and other questions about the water heater.

To answer your questions, I don't know what the supply pressure is from the water dept, but I'm sure I could find out. I do not see an expansion tank at all, anywhere near the water heater (which is about 20 ft from the PRV) in the garage. We never hear the sound after we turn off the water its only during while its running.
If you have more info, I'd appreciate.
Thanks

With a PRV you have a closed plumbing system so an expansion tank should be installed regardless of whether it is involved in this problem or not. Expansion tanks are current code and make life a lot easier on faucets, appliances and the water heater.

PRVs can be rebuilt but usually are replaced. If the PRV is right there in the garage then $675 sounds REALLY high unless that plumber is including the cost of installing a thermal expansion tank also. If he's not then you need to call in another plumber for a second opinion and tell them you want a thermal expansion tank installed also.

I just came back from Lowes with the gauge. The outside spickets measure about 84. Which from what I'm told isn't all that bad, I think we are suppose to be around 80. I just went out and checked the water heater, there is nothing that looks like the blue expansion tank in your picture. Since we replaced this about 3 years ago, is the code for one of these expansion tanks new? We were going to drain the water heater to see if that helps with the noise. And look into having an expansion tank installed or perhaps a new heater altogether.
Thanks for all your help, you have no idea how much we appreciate it.

IIRC, and maybe plumbers on this forum will chime in, code requirements for thermal expansion device in closed plumbing systems goes back to the mid 90's. Some PRVs include a check valve for thermal expansion control, but a thermal expansion tank is the most common solution and easy to check on a regular basis. If a thermal expansion tank is installed properly most homeowner's can easily replace them when and if they fail.

If you got the gauge with the tattletale needle then run the hot water till the water heater kicks in and then wait and watch the needle without opening any faucet in the house. If there's no thermal expansion device installed then the static pressure will rise well over 100 psi.

The thermal expansion situation is one thing and your noise is another. You may have a failed PRV and that needs to be addressed.

So we did some investigating....the only time we hear that specific noise is when any of the hot water in the house is turned on, when I switched to cold water, the noise stops. Lowes did not have the gauge with the tattletale needle, I looked at two different ones and they told me they didn't carry those.

So while I understand that the thermal expansion is one thing and the noise is another...could there be the possibility that the water heater needs to be drained. We have extremely hard water here. Could it be clogged to the point that its causing more pressure than is normal, which in turn is causing the noise? I just want to make sure that I'm fixing the right problems first, especially at $675 (which I might add was told was with the 10% "teachers discount" off of the original $750 cost) (cause no one ever checks) If that isn't the case then I will go ahead with the replacement of the PRV. But I do think I will get a second opinion first. I will definitely find out about a thermal expansion tank also.
Thank you so much !

Your PRV may be working fine and once you know the service pressure from the city you'll know if it is. Have the PRV adjusted down to 60-65 psi.

EVERYONE who has a water heater should be routinely draining it annually ESPECIALLY if you have HARD water and no softener. Around here the average life of a WH is 1.5 to 2 years and we have hard water. I have a softener and my WH is a little over 15 years old and still working perfectly. When draining every spring nothing but clear water comes out. If you are hearing the noise in the WH then there is already a significant buildup of solid stuff inside and there's nothing you can do.

If you want to cure the disease get a water treatment pro in there to quote you a quality water softener (no big box store junk), replace the water heater, and install a thermal expansion tank... then you're done. Oh yea... find another plumber that will charge a fair price to every one of his/her customers.

I do have a water softener. It's a Culligan Water Conditioner. Its really hard to try and teach yourself this stuff. It's hard to know about everything. That's why I came on here and searched the internet. The last time we had the heater drained was about 15 months ago. (I know we should have done it this past spring)

The house we live in was built in 2001. It's in Nevada. We thought it was a great house until 3 months after we moved in we received a letter from an attorney saying we had "kitec" piping and that it was bad.....long story short, we've already had all of the piping replaced in the house, been here only 4 years. So we've pretty much been through the mill. This PRV thing I hadn't heard of before. And we're not hearing the noise in the WH, we are hearing it at or near the PRV, and only when we are running hot water, never cold.

so we were just thinking (cause we really don't know about this stuff) that the noise could be something to do with the water heater.

You say to have the PRV adjusted down to 60-65 psi. Do I direct the plumber what he should do first? I don't mind paying for a service, believe me I don't, but I don't want to get ripped off either.
Thanks again.

Every post you make we get more info and are starting to get a picture of what's going on but without the details no one can help you through a keyboard.

I missed asking you an obvious question... has this noise always been there or is it a new noise? If a new noise, has anything changed recently in the plumbing? New sprinklers or irrigation? New washer? New dishwasher? Anything new? Do you usually use the irrigation along with other appliances? You may not have sufficent SFR (Service Flow Rate) to accommodate the irrigation along with a high water usage appliance.

The PRV is connected at the water service entrance from the meter. The PRV is in the line before it splits off to cold for the house and the cold feed for the WH so turning on a hot faucet and getting a noise at the PRV but turning on a cold faucet and not getting the noise at the PRV is confusing if what you are calling a PRV is a PRV. Can you post a picture of what you are calling the PRV?

If you water softener is sized and setup correctly for your water conditions and water useage you should have 0 hardness water all the time except when the softener regenerates. If your water is not 0 hard then the softener is not working properly, but that is another situation from this noise. when was the last time the softener was serviced? Has anyone checked post installation to see that the softener is functioning correctly and completely softening the water?

At this point put your chips down on a second opinion from another plumber. Simply tell the plumber about the noise and see what they say. Don't offer any other info cause you're looking for the plumber to do his/her job and identify the problem and quote you a price to correct it.

I think there may have been a little noise but nothing that I thought it was odd. A month ago we had a total front re-landscaping. We're running two times a day a lot of emitters. Would insufficient "service flow rate" cause noises when I'm trying to run, say, the washing machine? Perhaps the added water usage is doing this?

The Pressure Reducing Valve (what the plumber called it) is along the wall of the garage connected to the incoming pipes right along side the whole house water shut off valve. I'm not sure how to post a picture but its a Watt's model, I checked. It looks very similar to the the ones on their website.

I think you think that I'm referring to the pressure relief valve on the water heater, I'm not. The water softener was serviced just last year and has been running excellent and believe me with the water we have here, you notice right away when there's a problem.

Again, I can't thank you enough for the suggestions today. I am going to call another plumber in the morning for another opinion.
Thanks

Perhaps the people who installed that system didn't size it properly to the SFR of the house and you are experiencing a severe pressure drop when using the irrigation and another major water appliance like the washer. When the washer changes to a different cycle you're getting water hammer at the service inlet (the PRV).

If that is the case then I don't know which the better fix is... downsize the irrigation system OR only irrigate when nothing else is running OR increase the SFR to the house which I'm sure will cost a lot of $$$.

You don't want water hammer cause it's not just noise. It's the sound of pipes and joints vibrating and dancing around. Sooner or later something will fail and you'll have water where you don't want it.

If I'm on the right track I'd downsize the irrigation system. Besides, people in Nevada shouldn't be watering the desert ;)

The new irrigation is just about a month old and I guess I just never noticed any kind of noise like I do now. I did some searching on line and it said that noisy pipes could definitely be a pricy problem in the future. It didn't dawn on me that the irrigation system may be too much for SFR. How can I find out if that's the case? I don't want overkill and fix something that it might not even be, I want to make sure I get it right the first time, so this is great that you guys are asking all these questions.
I will call another plumber tomorrow and get a second opinion.
Thanks again and I'll let you know what happens.

Was the irrigation system installed by a licensed landscaper or plumber or was it DIY?

That series PRV has a thermal expansion bypass but I'd still want a thermal expansion tank because some codes prohibit expansion (back flow) into the mains. It does have an integral SS strainer that may be clogged and can be serviced through the bottom plug. Did you notice that it's setting range is 25-75 psi and standard setting is 50 psi so 80 psi is a touch on the high side.

The landscaping was 2 years in the planning, large landscaping company (yes, licensed) did the install and construction. But I don't recall any talk about SFR. This is the thing, my husband and I both work full time so there's not much time for DIY. I just hate to feel like I'm being taken advantage of because I don't know about something. But trying to be realistic....who knows about everything? I try to read up and investigate as much as I can but it's pretty impossible to know all the time when you're getting ripped off. After going back and forth with you yesterday, I think there were a lot of things that the plumber could have looked at or tried before he came up with the conclusion that PRV needed replacement. I mean he didn't even take out a gauge and check the pressure or anything....so that kind of gave me a red flag right there.
Thanks again and I'll keep you posted.

Thomas Hardy said "try to learn something about everything and everything about something" but it's awful hard to do.

I find it difficult to believe that a licensed landscaper would design and install an irrigation system without considering the service flow rate of the plumbing. In reality they are adding X many faucets around the lawn and that will have a profound effect on the appliances and fixtures in the home when they are on. Do we add 5 drip stations, 10, 100? How many will the plumbing system and flow rate support?

You might call the landscaper and tell them you're having a problem. See what they say although after two years they may not care, but maybe they would and could offer their experience and advice.

Perhaps the simple solution is to divide the irrigation system into smaller zones and decrease the demand into smaller demands over a lengthier time period.

The resolution to your problem may be as simple as cleaning the screen in the PRV or more complicated.

I don't think your plumber is trying to rip you off I believe he is operating at the level of his skill and knowledge. Your problem requires more than a faucet replacer.

If I were in your situation, as frustrating as it will be, I'd search till I found a plumber who made you feel secure in his/her knowledge. A plumber who did pull out a gauge and check the pressure. He or she may be hard to find but the search will be worth the trouble. Perhaps call your local plumber's union and ask for a list of master plumbers.